SIRIUS S0 power contactor, screw terminals, varistor suppression
The Siemens 3RT1024-1CP04 is a SIRIUS S0-frame power contactor for motor switching in control panels, with screw-type main circuit terminals and a built-in varistor surge suppressor. It mounts via screw or snap-on to a 35 mm DIN rail per EN 50022, fitting a 45 mm wide slot in the enclosure. Rated motor output reaches 7.5 kW at both 500 V and 690 V, with an AC-4 switching current of 12.5 A at 400 V — this is the reversing or inching duty rating, not the continuous AC-3 figure, so it governs frequent jogging applications.
Coordination and protection
For type 2 coordination (no damage to the contactor after a short circuit) the required upstream fuse is gL/gG 25 A. Type 1 coordination allows a 63 A gL/gG fuse. The varistor integrated across the coil suppresses voltage spikes during de-energization, reducing stress on the control circuit. Auxiliary contact ratings are specified per voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 0.3 A at 220 V — the DC switching curve drops sharply above 60 V (2 A at 60 V, 1 A at 110 V). Use these numbers for pilot duty and PLC input circuits, not the main contact ratings.
Environmental and physical fit
Operating temperature range is -25 to +60 °C, with a maximum altitude of 2 000 m without derating. The front face carries IP20 protection (finger-safe), while the terminals themselves are rated IP00 — keep live parts behind a panel door or cover. Pollution degree 3 means the contactor tolerates conductive dust and humidity typical of industrial enclosures. Dimensions are 88 mm height, 45 mm width, and 140 mm depth — the depth is the critical clearance behind the DIN rail for wiring and arc chamber ventilation. Side-by-side mounting is allowed without derating if ambient stays within limits.